1. Field of the Invention
The present invention relates generally to medical devices, and more particularly to a safety device to protect medical personnel from accidental puncture by a needle by using a protective sheath to surround the needle tip after a catheter is inserted into a patient and the needle is withdrawn.
2. Description of Related Art
Catheters and safety needle devices are well known in the art. These devices have been developed because it is necessary to protect against the possibility of accidental needle stick. Various life-threatening diseases such as hepatitis and acquired immune deficiency syndrome (AIDS) make needle protection a serious matter. Needles and syringes are used for a variety of purposes in a clinical environment such as injecting drugs or withdrawing blood. More recently, it has become common practice to use a needle to aid in the insertion of a flexible intravenous (IV) catheter into a vein. IV catheters are used to alleviate the trauma of repeated injections and the discomfort associated with leaving a needle in a patient for an extended period. There are two types of IV catheters: through-the-needle catheters, in which a catheter is threaded through the needle into the vein of a patient, and over-the-needle catheters, in which a catheter is placed over the needle and inserted simultaneously with the needle, staying in the vein when the needle is withdrawn. The needle is used to puncture the skin and locate the vein; thereafter the catheter is slid over the needle and into the vein, staying in position so that periodic administration of fluids, drugs, transfusions, and collecting of blood samples is possible.
The process of inserting an over-the-needle catheter into a vein usually requires the needle tip to be exposed once withdrawn from the patient. Often times, the needle will be set down while other urgent procedures are attended to, and taken to a sharps container at a later time. In all such needle applications, the tip of the needle is exposed from the time it is withdrawn from the patient up until the time it is placed in a sharps container. Therefore, there is a need for a protective device of some kind to fit over the needle to protect against accidental exposure of medical personnel to pathogens left on the needle from the patient's blood.
Much of the prior art in this field requires an extra step to be performed by the user to ensure protection from the needle tip. For example, U.S. Pat. No. 5,569,217 to Luther is directed to a percutaneous port catheter assembly and method of use. A protective casing is slidably mounted within the housing. The casing is mounted in a manner that allows the casing to pass axially through the passage orifices of the base. At the proximal end of the casing, a protective cap is provided which has an outer surface that is used to press the casing through the housing. By requiring the user to push the casing through the housing after removal of the needle, however, there exists the possibility that the user will forget or neglect to do so, thereby rendering the safety device useless.
Some prior art, thus, addressed the problem by implementing automatic sheathing systems. One of the first to do so was McDonald in U.S. Pat. No. 4,944,725. This patent is directed to an automatic covering system for an intravenous catheter. The system includes a needle, handle means for manipulating the needle, a protective housing means to cover the needle, a latch means to prevent unwanted movement of the needle, and locking means to lock the catheter to the housing for insertion. An over-the-needle catheter is introduced into the patient, and the needle is withdrawn into the protective housing without the needle being exposed. Latch means, in the form of latching fingers formed on diametrically opposite sides of the housing, and an annular latch detent formed on the shell, eventually lock together to permanently trap the needle tip inside the passage.
U.S. Pat. No. 5,769,827 to DeMichele et al. improved upon the McDonald device by adding a cap to provide additional safety. The protective cap is frusto-conical and has a larger somewhat cylindrical end opposite a narrower cylindrical end that is mountable on the narrowed cap-mounting hub on the needle housing. The catheter hub mounts on the catheter mount and is retained in place by radially extending arms. The larger end of the cap has an internal radial rib and the handle housing has a mating radial detent on the needle end of the handle housing. The larger end of the cap is mounted on the needle end so that the cap's internal rib abuts the radial detent in the housing.
While the automatic sheathing devices were an improvement on the needle protectors that required an additional step after withdrawal of the needle, they are still deficient in that they are complex, involving numerous steps to operate, impractical in their design, and costly to manufacture. Thus, there exists a need for a simple, easy to use, and cost-effective automatic sheathing device to protect against accidental needle stick.